C语言结构体如何改代码

原始 inventory.c如下
#include<stdio.h>
#include "readline.h"

#define NAME_LEN 25
#define MAX_PARTS 100

struct part
{
int number;
char name[NAME_LEN + 1];
int on_hand;
}inventory[MAX_PARTS];

int num_parts = 0; /* number of parts currently stored */

int find_part(int number);
void insert(void);
void search(void);
void update(void);
void print(void);

/**

• main: Prompts the user to enter an operation code,

•     then calls a function to perform the requested
  

•     action. Repeats until the user enters the
  

•     command 'q'. Prints an error message if the user
  

•     enters an illegal code.
  

• /
  int main(void)
  {
  char code;
  for(;;)
  {

    printf("Enter operation code: ");
    scanf(" %c", &code);
    while (getchar() != '\n'); /* skips to end of line */
    switch (code)
    {
    case 'i': insert(); break;
    case 's': search(); break;
    case 'u': update(); break;
    case 'p': print();  break;
    case 'q': return 0;
    default: printf("Illegal code\n");
    }
    printf("\n");
  

  }
  }

/**

• find_part: Looks up a part number in the inventory

•          array. Returns the array index if the part
  

•          number is found; otherwise, returns -1.
  

• /
  int find_part(int number)
  {
  int i;

  for (i = 0; i < num_parts; i++)

    if (inventory[i].number == number)
        return i;
  

  return -1;
  }

/**

• insert: Prompts the user for information about a new

•       part and then inserts the part into the
  

•       database. Prints an error message and returns
  

•       prematurely if the part already exists or the
  

•       database is full.
  

• /
  void insert(void)
  {
  int part_number;

  if(num_parts == MAX_PARTS)
  {

    printf("Database is full; can't add more parts.\n");
    return;
  

  }

  printf("Enter part number: ");
  scanf("%d", &part_number);
  if(find_part(part_number) >= 0)
  {

    printf("Part already exists.\n");
    return;
  

  }

  inventory[num_parts].number = part_number;
  printf("Enter part name: ");
  read_line(inventory[num_parts].name, NAME_LEN);
  printf("Enter quantity on hand: ");
  scanf("%d", &inventory[num_parts].on_hand);
  num_parts++;
  }

/**

• search: Prompts the user to enter a part number, then

•       looks up the part in the database. If the part
  

•       exists, prints the name and quantity on hand;
  

•       if not, prints an error message.
  

• /
  void search(void)
  {
  int i, number;

  printf("Enter part number: ");
  scanf("%d", &number);
  i = find_part(number);
  if(i>=0)
  {

    printf("Part name: %s\n", inventory[i].name);
    printf("Quantity on hand: %d\n", inventory[i].on_hand);
  

  }
  else
  {

    printf("Part not found.\n");
  

  }
  }

/**

• update: Prompts the user to enter a part number.

•       Prints an error message if the part doesn't
  

•       exist; otherwise, prompts the user to enter
  

•       change in quantity on hand and updates the
  

•       database.
  

• /
  void update(void)
  {
  int i, number, change;

  printf("Enter part number: ");
  scanf("%d", &number);
  i = find_part(number);
  if(i >= 0)
  {

    printf("Enter change in quantity on hand: ");
    scanf("%d", &change);
    inventory[i].on_hand += change;
  

  }
  else
  {

    printf("Part not found.\n");
  

  }
  }

/**

• print: Prints a listing of all parts in the database,

•      showing the part number, part name, and
  

•      quantity on hand. Parts are printed in the
  

•      order in which they were entered into the
  

•      database.
  

• /
  void print(void)
  {
  int i;

  printf("Part Number Part Name "

    "Quantity on Hand\n");
  

  for (i = 0; i < num_parts; i++)

    printf("%7d            %-25s%11d\n", inventory[i].number,
        inventory[i].name, inventory[i].on_hand);
  

  }